A computerized methodology for analyzing autoradiographic spot images associated with recombinant DNA bacterial colonies was developed in collaboration with scientists in NCI. This system represents a unique refinement in a method to directly identify cloned sequences complementary to messenger RNA that are developmentally or hormonally induced. Spot density measurements are computed from digitized images produced via microdensitometry. These measurements are corrected for variability in exposure and local background, calibrated to hybridization standard, and normalized for comparison purposes. The system provides a variety of graphical and tabular output that effectively summarizes experimental results and identifies significant induced hybridization events. A paper illustrating an application of this system was prepared and submitted for publication.